A robot hand that includes paired main fingers and an auxiliary finger is well-known (for example, see PTL 1). The paired main fingers nip a workpiece as a working object from both sides to hold the workpiece, and the auxiliary finger comes into contact with the workpiece at a position different from positions of the main fingers. In the robot hand disclosed in PTL 1, the main fingers are rotated to be brought into close contact with a surface of the workpiece when the main fingers hold the workpiece.